Light hydrocarbons



Aug. l1, 1959 G. J. sTEEvEs CRUDE on. CENTRIFUGING PROCESS Filed Sep. 2,1955 .E23 ...www 3.o M305 .103 @22u56 CRUDE OIL CENTRIFUGINGPROCESSGeorge J. Steeves, Woods Cross,4 Utah, assignor to Phillips PetroleumCompany, a: corporation 'oilelawaren Application September Z, 1955,Serial '-No. 532,250

8 Claims. (Cl. 208-39) This inventionrelates to the separation ofmaterials fromwadmixture with each other by centrifugation. In oneaspect, this invention relates to a centrifugingfprocess for the removalof impurities fromy oils. InY still vanother aspect'thisinvention-relates to the separation ofsolids, semi-solids, and heavyliquid materials, all as-impurities, from a crudeoil, by centrifugationand maintaining in the centrifugation zone a-liquid'hydrocarbon having aspecic gravity higher than that of-thesaid oil at centrifugingconditions; In 1 still another aspect,1 this invention relates to acombination of steps wherein a crude petroleum oil isprocessed-,.including a centrifugation step, andV wherein `a liquidhydrocarbon fraction especially suitable for improving throughput of thesaid centrifugation, is formed, and is cycled tothe said centrifugationstep.

In the copending application of D. W. Gagle, G. J. Steeves and R. F.Berger, Serial Number 514,262, led June 9, 1955, is disclosed andclaimed a1 ycentrifugirig method for removal of undesirable componentsfrom crude oils wherein the centrifugation temperature is maintainedbelow about 100 F., preferably inthe range of about 30 to 80 F., morepreferably from 40v to 701 F.,

ywhereby asphaltic components of theoil, subsequently recovered, exhibitmarkedly improved properties particularly in respect ofV penetration,ductility, solubility in carbon tetrachloride, solubility inV carbondisulfide, and the Oliensis spot test, whereas asphalts ordinarilylrecovered subsequent to centrifugation of the crude attemperatures'outside the above ranges exhibit borderline specificationsas to properties suchiasthe foregoing. n

This invention is concerned'with a` method yfor improving the amount-ofcrude oilthat canV becentrifuged per unit time when employingacentrifugationl suchl as'that re- Iferred to with reference tothe abovesaid'copending application.

An object of this invention is to provide for removal of impurities fromoils. Anotherobjectis to ,provide for an increase in the amount ofacrude oil'that can becentrifuged per unit time. Another object is to.provide a combination of steps containing a centrifugation step, in

which combination is produced a liquid hydrocarbon fraction whichisespecially suitable for cycling `tothe centrifugation step to increasethe amountofmaterial that can be centrifuged therein per unit time.Another object is to provide steps for centrifuging anasphalt-containing crude oil whereby to provide for recovery fromresulting crude, asphaltproduct exhibiting markedly irnprovedproperties, particularly with reference'to penetration, solubility, and,spot test above-referred. to. Another object is to provide forincorpo-ration of a selected hydrocarbon fraction in an oilundercentrifugation conditions wherebyto markedly increase the amount ofoil vthat can. be4 centrifuged per unit-time. Otherl aspects and objectsof this inventionvand its^several relatedparticulars :in-gs, and theappendedclaims.`

In accordance with this invention, an oil containing impurity -materialsseparable by centrifugation-is centrifuged in the presence of an addedhydrocarbon having a specific-gravity higher than that of the said oil,whereby tomarkedIy increase the amount of said- Oil that can .becentrifuged to remove the-,said impurities, per unit time; theinventionproviding a process inaccordance withk an'- other concept, comprisingcentrifuging va crude petroleum oil containingimpurities, removable bycentrifugation, in -the presencefof a vhydrocarbon fractionas describedhereinafter, topping resultinggimpurity-free crude'oil to separate atopped crude and a .gas oil fractionxtherefrom, vacuum reducing saidtopped crude to form asphalt and gas =0il fractions, cracking atleast'one of said gas oils, recovering a light cycle oil from saidycracking and recycling same to said centrifuging step, whereby theamount of oil 1'centrifuged perunit time is markedly increased, andrecovering said asphalt as a product of the process.,

Any oil mutually solublezwith the -added hydrocarbon and-containingimpuritiesV substantially-insoluble in the said hydrocarbon whichimpurities can'- be separatedvr from the oil byv centrifugation',- canbe treated in accordance with this;invention,although the inventionin anow preferred form is applied' to crude petroleum oils.- Exemplary ofoilsother than-crude petroleumA oils which. can be treated in accordancewith this invention are residual fuel oils,l thermally cracked ;oils,.and the like; exemplary of various types-ofcrude petroleum oilsprocessed in accordance Vwith this invention are Rangely (Colorado),Williston Basin (NorthDakota), Bowes Dome (Montana) 'and Sant-a Maria-(California) crude oils.

Crudeoil impurities removable in the practice of this invention aresolid, semi-solid, and heavy liquid ma- .terials generally present inthe crude, on a weight basis, withinwa range Vof about 0.5 to 10.0percent. Theyv are substantially insoluble in the oil from which they,are to be removed and haven-specific gravity-higher than that oil Vandvhigher than that of. the-hydrocarbon added Vto the said oil. Among suchimpuritygmaterialsare those which `havefbeen identied as insol-ubleincarbon disulfide, carbon tetrachloride, standard naphtha, and'xylene-normal heptane.

Anyi hydrocarbonl fraction having. a specific gravity h-igherthan'thatofthe .oil treated; can be employed in the practice of this invention;i.e;, for incorporation into the oil-in the centrifugation system,`apreferred-hydrocarvbonfraction being -one havingY a pour point-belowabout 70 F., preferably -in they range of-v about -45 to 30 F. and aviscosity below about 60, preferablyin the range of about'32 to 50seconds (SUV @D 100 F.). Exemplaryof suitable hydrocarbon fractions thatcan be added tofthecentrifugation system in accordance with thisinvention are. light cycle oils, heavy cycle oils, decant oils, and:other oils having relatively low pour points, low-viscosities, andhigher specific gravities than the oil being processed.

Although added hydrocarbon fractions havinga pour point outside theabove-described pour point range .and/ or a viscosityfoutside the'abovedescribedy viscosity range can'be employed in the practiceof'thisinvention, such fractions are less preferred because the higher'pour points and viscosities prevent optimum :operation of the.centrifuging step at the desired temperature range.`

Thexvolume ratio of added hydrocarbon to crude oil treated. is generallywithinl the range of 0.005 to 0.2:1 although values outside thisrangecanvbe employed when desired. However, ratios outside this range are lesspreferred'because below theselimits, the :extent of improve- .ment in4throughput is often only slight,` and @above these lrnits;l the`handling of the recycle -is often lnot 'desirable froman'econornicpoint of View.

Preferred centrifugation temperatures are in the range of 30 to 85 F. asset forth in the copen-ding application referred to herein wherebyasphalt subsequently recovered has been found to exhibit unpredictedimproved properties particularly with reference to penetration, spottest and solubilities in carbon disulfide and carbon tetrachloride.

My invention is illustrated with reference to the attached drawing whichexemplies a combination process containing7 a centrifugation step inwhich process a hydrocarbon fraction suitable for addition to thecentrifugation step therein, in accordance with this invention, isformed, and cycled to the said centrifugation step. With reference tothe attached drawing, a crude oil of the type described herein, as, forexample, a Rangely, Colorado, crude, having a specic gravity in theorder of about 0.85 (a typical range of crude oil gravities being fromabout 0.80 to 0.93), is passed via line 1 and heater 2, or cooler, asrequired, wherein it is heated or cooled to a temperature below about100 F., preferably in the range of from about 30 to 85 F., intocentrifuge 3 which can be of the Merco type. A cycle oil describedhereinafter is also introduced into the centrifuge element 3 by way ofline 6. Centrifugation is conducted in centrifuge 3 at a temperaturewithin the said range whereby impurities are separated and are withdrawnlby way of line 5 and improved crude oil, i.e., free from impurities, isseparated and withdrawn by way of line 4 and preheater 4 wherein it isheated to a temperature for topping such as in the range of about 600 to800 F. Crude oil in line 4 is passed into topping unit 7 wherein variousfractions are separated and are withdrawn as light hydrocarbon gases vialine 8, gasolines via line 9, distillates via line 10, gas oils via line11, and residual topped crude via line 12. Topped crude from line 12 ispassed to vacuum reduction unit 13 wherein it is vacuum reduced toproduce a vacuum gas oil fraction and a residual asphalt fraction, theformer being withdrawn via line 15 and the latter via line 14. Vacuumgas oil in line 15 and gas oil in line 11 are together, or one alone, asdesired, charged via line 15 to cracking zone 16 which can be thermal orcatalytic. In vacuum reduction zone 13, the pressure employed isgenerally in the range of from about 5 to 75 mm. Hg, the initialreduction temperature being generally that of the topped crude withdrawnfrom zone 7.

Cracking in zone 16 is advantageously carried outrat a temperature inthe range `of about 800 to 1000 F., a contact time in the range of about1 to l5 seconds being generally preferred which when employing acatalyst is in terms of space velocity, from about 0.3 to 7.0 pounds ofthe vapor feed per' pound of catalyst per hour. Cracking pressuresemployed are those Within any suitable range such as in the range of 0`to 20 p.s.i.=g. Exemplary of cracking catalysts that can advantageouslybe employed in cracking zone 16 are, e.g., natural and synthetic claytype catalysts, etc. Product fractions from cracking in zone 16 are alight hydrocarbon fraction withdrawn via line 17, cracked gasolineswithdrawn via line 18, a light cycle oil withdrawn via line 18', a heavycycle oil withdrawn via line 20, and a decant oil withdrawn via line 21TGas oil feed streams to cracking zone 16, i.e., in lines 11 and/or 15,generally have a boiling range within the limits of 400 to 1100 F.

The light cycle oil fraction withdrawn from zone 16 by way of line 18for cycling to centrifugation zone 3, I have found, is especiallysuitable for that purpose, the throughput in zone 3 in terms of crudeoil processed, being substantially doubled as compared with thatpossible without cycling of the said cycle oil in line 6 thereto. Lightcycle oil in line 6 has a pour point generally in the range of -30 to 30IF., a viscosity inzthe range of about 35 to 40 SUV at 100 F., and aspecific gravity in the range ofabout 0.907 to 0.93, and higher thanthat of the crude oil processed in zone 3. The ratio of cycled oil fromline 6, to that of crude oil from line 1, on a volume basis, isgenerally in the range of 0.005 :1 to 0.3:1 dependent to an extent uponthe specic crude being processed. Thus, when processing a Rangely,Colorado, crude, as referred to herein, the light cycle oil fraction hasa specific gravity in the order of about 0.914, the specific gravity ofthe said crude being about 0.852, and has a pour point of about zero,and is cycled to Zone 3 in a volume ratio to the said crude oil of about2 percent.

The following examples illustrate my invention and particularly pointout that a markedly improved throughpoint of crude oil is obtained inthe centrifugation step when incorporating a hydrocarbon fraction in thesaid step, having a specific gravity higher than that of the crude oilprocessed. In Table I are data giving a comparison of the properties ofasphalt products produced by treatment of Rangely crude according to theinvention wherein light cycle oil is recycled separately into thecentrifuge (column A), asphalt products produced by treatment of thesame crude by the method of the aboveidentified application Serial No.514,262 (column B), and asphalt productsvproduced from the same crudewhich has not been centrifuged (column C). Ihese examples show that theamount of crude oil that can be processed in the practice of thisinvention can be substantially doubled as compared with that otherwisepossible. l

Table I A B C Gallons per hour centrifuged, maximum throughput l, 500750 Light cycle oil recycle. gal/hr 30 Temperature of ecntrlt'uginiy FTreated crude recycled, gal./hr Asphalt:

Standard naphtha (30 min.) Neg Neg Pos 35-65% xylene-n-heptane (30 min.)Neg Neg Pos Cut back asphalt:

Gravity, API at (iO/60 F 13. 1 13.0 13. 4 Flash, tag open cup, F. 80+80+ 80+ SUV at 140 F., sec 320 215 325 Distilla 'our Vol. percent oftotal distillate to 680 F.-

Penetration, 5 see., 100 gm., 77 F 89 8S 92 l Ductility, 5 cm./min., 77F., cm 150+ 150+ 145 Sol. in C014, 77 F., Weight percent 99. 69 99. 7008. 9 Sol. in CS2, 77 F., weight percent 99. 0 Oliensis spot test:

Standard naphtha (30 min.) Neg Neg Pos 35-65% xylene-n-heptane (30 min.)Neg Neg Pos Diesel fuel:

API at (S0/60 F 34. 8 34. 7 34. 8 IBP, F 337 342 338 10% evap., (vol.),F 493 495 490 evap., F 609 60S G04 End point, F--. 640 642 638 Pourpoint, F -5 -5 +10 Flash point, tag closed cup, 154 156 154 "within thescope of the foregoing disclosure, the drawing,

and the appended claims to the invention, the essence of which is thatin the separation of impurity materials Vfrom an oil containing the sameby centrifugation, the Vimprovement is provided'comprising adding to thezone of the'said' centrifugation a hydrocarbon having a specific gravityhigher than that of the said oil whereby -substantally improvedthroughput of oil in the centrifugation zone is achieved,crudepetroleumoils being processed in accordance with -a now preferred form of theinvention; the invention in accordance with another concept providing acombination of steps wherein a crude petroleum oil is processed,including a centrifugation step, and wherein a liquid hydrocarbonfraction especially suitable for improving throughput of the saidcentrifugation, is formed, and is cycled to the centrifugation, all asdescribed herein.

I claim:

1. A separation process comprising passing a crude petroleum oilcontaining impurities removable by centrifugation into a centrifuge,centrifuging said crude petroleum to separate said crude petroleum oilinto an oil phase and an impurity phase, adding directly to said oilphase undergoing centrifugation in said centrifuge a hydrocarbon oil as.a separate stream having a specific gravity higher than that of saidcrude petroleum oil and mutually soluble therewith, said addedhydrocarbon oil having a lower specific gravity than said impurities,said impurities being insoluble in said added hydrocarbon oil andrecovering an oil fraction of reduced impurity content.

2. The improvement of claim l wherein said oil is a crude oil, saidhydrocarbon has a pour point in the range of 'about -45 to 30 F., aviscosity inthe range of about 32 to 50 SUV at 100 F. and a specificgravity in the range of about 0.907 to 0.93 and the temperature of saidcentrifugation is below about 100 F.

3. A process comprising passing a crude petroleum oil containingimpurities removable by centrifugation into a centrifugation zone; alsoseparately passing into said zone a separate hydrocarbon streamdescribed hereinafter; centrifuging the resulting crude oil-hydrocarbonmixture in said zone at a temperature below about 100 F. to separatesaid impurities; withdrawing impurities from said zone; passingremaining crude oil-hydrocarbon admixture from said zone to a toppingzone, and topping said crude oil therein; separating a gas oil fractionand a residual topped crude fraction in said topping zone andwithdrawing each said fraction therefrom; passing said residual fractionto .a vacuum reducing zone and therein separating same into a residualasphalt and a gas oil fraction; passing at least one of said gas oilfractions to a cracking zone and therein cracking same to producecracking product including a light cycle oil; cycling said light cycleoil to said centrifugation zone as the said hydrocarbon fraction addedthsreto, above described `whereby the amount of crude oil centrifugedper unit time is markedly increased, and recovering said asphalt asproduct.

4. A process of claim 3 wherein the specific gravity of said crude oilis in the range of from 0.80 to 0.93, the pour point of said cycle oilis in the range of about -45 to 30 F., the viscosity of said cycle oilis in the range of about 32 to 50 SUV at 100 F., and the volume ratio ofsaid cycle oil to said crude oil is in the range of 0.005:1 to 0.2:l.

5. A process of claim 4 wherein said crude oil is a crude selected fromthe group consisting of Rangely (Colorado), Williston Basin (NorthDakota), Bowes Dome (Montana), and Santa Maria (California) crude oils.

6. A process of claim 4 wherein said cracking is effected at atemperature in the range of 800 to 1000" F. at a contact time of from 1to 15 seconds and each said gas oil has a boiling range wi-thin thelimits of about 400 to 1100 F.

7. A process of claim 6 wherein said cracking is carried out in thepresence of a catalyst selected from the group consisting of naturalcatalyst and synthetic clay type catalysts.

8. A process of claim 2 wherein said hydrocarbon fraction is selectedfrom the group consisting of light cycle oils, heavy cycle oils, `decantoils, and combinations thereof.

References Cited in the le of this patent UNlTED STATES PATENTS1,901,010 Sweetland Mar. 14, 1933 2,052,124 Anderson Aug. 25, 19362,166,893 Holsten July 18, 1939 2,176,982 Thayer Oct. 24, 1939 2,305,440Noel Dec. 15, 1942 2,443,840 Stossel June 22, 1948 2,446,040 Blair July27, 1948 2,619,280 Redlich Nov. 25, 1952 2,662,051 Pelzer Dec. 8, 1953OTHER REFERENCES Egloff et al.: Petroleum Technology, 'vol. 1, No. 2,May 1938, pp. 15 to 19.

ASTM, D96-50T, Water and Sediment by Means of Centrifuge, issued 1947,ASTM Standards.

3. A PROCESS COMPRISING PASSING A CRUDE PETROLEUM OIL CONTAININGIMPURITIES REMOVABLE BY CENTRIFUGATION INTO A CENTRIFUGATION ZONE; ALSOSEPARATELY PASSING INTO SAID ZONE A SEPARATE HYDROCARBON STREAMDESCRIBED HEREINAFTER; CENTRIFUGING THE RESULTING CRUDE OIL-HYDROCARBONMIXTURE IN SAID ZONE AT A TEMPERATURE BELOW ABOUT 100* F. TO SEPARATESAID IMPURITIES; WITHDRAWING IMPURITIES FROM SAID ZONE; PASSINGREMAINING CRUDE OIL-HYDROCARBON ADMIXTURE FROM SAID ZONE TO A TOPPINGZONE, AND TOPPING SAID CRUDE OIL THEREIN; SEPARATING A GAS OIL FRACTIONAND A RESIDUAL TOPPED CRUDE FRACTION IN SAID TOPPING ZONE ANDWITHDRAWING EACH SAID FRACTION THEREFROM; PASSING SAID RESIDUAL FRACTIONTO A VACUUM REDUCING ZONE AND THEREIN SEPARATING SAME INTO A RESIDUALASPHALT AND A GAS OIL FRACTION; PASSING AT LEAST ONE OF SAID GAS OILFRACTIONS TO A CRACKING ZONE AND THEREIN CRACKING SAME TO PRODUCECRACKING PRODUCT INCLUDING A LIGHT CYCLE OIL; CYCLING SAID LIGHT CYCLEOIL TO SAID CENTRIFUGATION ZONE AS THE SAID HYDROCARBON FRACTION ADDEDTHERETO, ABOVE DESCRIBED. WHEREBY THE AMOUNT OF CRUDE OIL CENTRIFUGEDPER UNIT TIME IS MARKEDLY INCREASED, AND RECOVERING SAID ASPHALT ASPRODUCT.